Argentina's state oil company YPF, Pan American Energy and Wintershall will invest $38 billion in the country's vast but mostly untapped Vaca Muerta shale formation, the governor of Vaca Muerta's home province of Neuquen said July 15.

The companies will use the new concessions to develop the Lindero Atravesado and Bandurria oil and natural gas fields, Governor Jorge Sapag said.

The $38 billion will be invested over the next 20 years, the first $1.4 billion from 2015 to 2018, he added.

"With Lindero Atravesado and Bandurrias we estimate that over the years ahead ... Neuquen will double its oil production and that the gas produced by these fields could replace more than 40 shiploads of imports, which would represents $1.6 billion in savings for Argentina," Sapag said.

The specific fields to be developed by the 35-year concessions are Lindero Atravesado, Bandurria Sur, Bandurria Centro and Bandurria Norte, the province said in a press statement.

Pan American will operate 63.5 percent of Lindero Atravesado and YPF 37.5 percent, a statement from the provincial government said. Bandurria Sur will be operated by YPF, Bandurria Centro by Pan American and Bandurria Norte by Wintershall, it said.

President Cristina Fernandez's interventionist policies had scared all but the most risk-hungry companies out of making anything but foothold investments in Vaca Muerta, which is viewed as one of the biggest shale reserves in the Western Hemisphere.

Latin America's No. 3 economy has struggled to attract the investment it needs to exploit Vaca Muerta and erase an energy trade deficit that costs billions of dollars per year, at times straining cash reserves already pressured lower by capital flight and lack of access to the international bond market.

The country has been unable to offer sovereign debt governed by international law since its 2002 bond default, which has been further complicated by lawsuits from holders who rejected the terms of Argentina's 2005 and 2010 debt restructurings, in which holders got about 30 cents on the dollar.